1. Field of the Invention
The present invention relates to a dielectric ceramic composition and a ceramic electronic device. Further specifically, the present invention relates to a dielectric ceramic composition combining specific permittivity and reliability, and a ceramic electronic device in which the dielectric ceramic composition is applied to a dielectric layer.
2. Description of the Related Art
Recently, with densification of electronic circuits, demands for downsizing of an electronic device are increased, which is associated with promoting downsizing and increase in capacity of for example a multilayer ceramic capacitor, and further improvements in properties are required.
In response to such a demand, by forming a dielectric particle included in a dielectric ceramic composition with two phases having different properties, improvement in various properties has been sought.
For example, the Japanese Unexamined Patent Publication No. 2001-230149 discloses a multilayer ceramic capacitor having a dielectric layer comprising a dielectric particle having a core-shell structure. It is disclosed that in this capacitor, a shell portion includes an acceptor-type element such as Mn; Mg; and a rare-earth element, wherein concentrations of the acceptor-type element and the rare-earth element included in the shell portion are gradually increased towards a crystal grain boundary from a boundary between a core portion and the shell portion.
However, in the capacitor disclosed in the Japanese Unexamined Patent Publication No. 2001-230149, because distribution of the rare-earth element in the shell portion is the above-described distribution, there is a problem that it is hard to combine specific permittivity and reliability.
Also, the Japanese Unexamined Patent Publication No. 2008-222520 discloses a dielectric ceramic composition comprising a dielectric particle having a surface diffusion structure which comprises a central layer substantially consisting of a main component and a diffusion layer surrounding the central layer in which rare-earth elements are diffused in the main component. It is disclosed that the dielectric ceramic composition has a feature that concentration of the rare-earth element inside the diffusion layer is higher than concentration of the rare-earth element near an interface between the diffusion layer and a crystal grain boundary.
However, in the dielectric ceramic composition disclosed in the Japanese Unexamined Patent Publication No. 2008-222520, specific permittivity may be low and specific permittivity and reliability may not fully be combined.